Immunoenhancement effect of neuraminidase on in vitro cell-mediated immunity in normal subjects and patients with a variety of neoplastic diseases will be studied. Immunotherapeutic effect of neuraminidase in tumor-bearing animals will be studied by direct injection of neuraminidase-treated lymphocytes into established intradermal tumors, by intravenous or intraperitoneal administration, and by infusion of neuraminidase-treated lymphocytes sensitized against tumor-associated antigen.